Antibacterial polymer

ABSTRACT

An antibacterial polymer containing a repeating unit of the formula ##STR1## wherein A, l and n are defined in the specification.

The present invention relates to an antibacterial polymer having quaternary nitrogen atom(s). The polymer is widely used for germicide for pool water, drinking water and cooling water, slime control agent, floor material, wall material, ceiling material or like building materials, agricultural materials, etc.

Among the conventional antibacterial compounds, a low-molecular one is used as admixed with a material constituting various products. In this case, the effective component having antibacterial activity is apt to release outwardly or to separate downward, consequently the antibacterial compound has a defect of being low in durability of antibacterial action.

Therefore, high-molecular compounds having antibacterial activity are developed to solve the above problems but sufficient results have not yet achieved.

An object of the invention is to provide an antibacterial polymer having an excellent antibacterial activity and durability in the activity.

The above and other objects of the invention will become apparent from the following description.

The present invention provides an antibacterial polymer containing a repeating unit of the formula ##STR2## l is 20 to 2000, n is a number of at least 1000, X and Z are the same or different and are an anion, R is alkyl group having 6 to 18 carbon atoms, m is an integer of 2 to 10.

In the antibacterial polymer of the present invention, the long-chain alkyl group R has preferably 6 to 18 carbon atoms but alkyl group of 8, 10 or 12 carbon atoms is more preferable in the viewpoint of antibacterial activity. Anions are not particularly limited and include Br⁻, Cl⁻, I⁻, NO₃ ⁻, CH₃ OO⁻ and SO₄ ²⁻. Preferably l is 20 to 2000, n is a number at least 1000 and m is an integer of 2 to 10.

The antibacterial polymer of the present invention is characterized in that the quaternary nitrogen atom is apart from the polymer main chain, the polymer is insoluble and high in antibacterial activity.

The antibacterial polymer of the present invention is preferably a spherical particle having a diameter of 2 to 10 mm. The present polymer is used as packed in a column, as suspended in water or in the form of a sheet obtained with use of a blend of the present polymer and other polymer.

The antibacterial polymer of the present invention exhibits wide antibacterial spectra over Gram positive bacteria and Gram negative bacteria. Further, the present polymer shows growth preventing effect over mould.

The following is an example of preparation of the antibacterial polymer of the present invention by use of reaction equations. ##STR3##

In the above reaction equation (1), the compound (H) is used usually in an amount of 1.0 to 2.5 moles, preferably about 1.1 to 2.1 moles per mole of the compound (P). The reaction is conducted preferably in a solvent and the reaction temperature is preferably about 60° to 110° C. The product (B) can be purified by a method such as concentration, distillation and recrystallization. The polymerization shown by the equation (2) can be carried out by a usual method such as suspension polymerization, solution polymerization and bulk polymerization. The obtained polymer is purified by a method such as reprecipitation and washing. In the reaction shown by the equation (3), the compound (B) is used usually in an amount of about 0.02 to 0.15 equivalent, preferably about 0.05 to 0.10 equivalent per equivalent of chlorine of the compound (PCS) or (PCS DB). The reaction is conducted preferably in an organic solvent and generally conducted at a temperature of about 60° to 100° C. The obtained (PCS-B) or (PCSDB-B) can be purified by a method such as reprecipitation and washing. Compounds wherein A is other than the above can be prepared in the similar reaction to the above.

The antibacterial polymer of the present invention has an excellent antibacterial activity and exhibits wide antibacterial spectra. The polymer is widely used for germicide for pool water, drinking water and cooling water or slime control agent. Further, the polymer is added to a synthetic resin and the like and is effectively used for preventing the growth of bacteria and mould in building materials, agricultural materials, etc.

The present invention will be described in detail by showing examples and test examples.

EXAMPLE 1

Into a 300 ml round-bottom flask equipped with a stirrer, reflux condenser, nitrogen-introducing tube and dropping funnel were placed 100 ml of ethyl alcohol and 31.2g (0.2 mole) of 4,4'-bipyridyl and thereto added dropwise 24.9 g (0.1 mole) of lauryl bromide through the dropping funnel over a period of 2 hours while introducing dry nitrogen and heating on an oil bath of 90° C. After heating and stirring for 18 hours, the solvent was removed and the residue was recrystallized from methanol/acetone to obtain 55g of N-lauryl-4,4'-pyridylpyridinium bromide (hereinafter referred to as "B"). The similar reactions were conducted with respect to other alkyl halides.

A homopolymer (PCS) of p-chloromethylstyrene (CS) was prepared by a conventional suspension polymerization. The polymer was washed with hot acetone to remove an unreacted monomer.

In 800 ml of methanol, 10 g of the above (B) and 200 g of the polymer PCS were reacted at 60° C. for 50 hours to obtain 208.3 g of the antibacterial polymer (PCS-B).

EXAMPLE 2

A copolymer (PCSDB) of CS and divinylbenzene (DB) was prepared by polymerization reaction in the same manner as in Example 1. The polymer was washed with hot acetone to remove an unreacted monomer.

In 800 ml of ethanol, 5 g of the above (B) and 200 g of the polymer PCSDB were reacted at 70° C. for 20 hours to obtain 204.5 g of the antibacterial polymer (PCSDB-B).

Each of the above antibacterial polymers had a formation rate of quaternary ammonium of about 90% by analysis with use of a solution of Bromophenol Blue (BPB) in methanol.

EXAMPLE 3

Into a 300 ml round-bottom flask equipped with a stirrer, reflux condenser, nitrogen-introducing tube and dropping funnel were placed 290 g (4.8 moles) of nitromethane and 13.5 g (0.086 mole) of 2,2'-bipyridyl and thereto added dropwise 44.7 g (0.18 mole) of lauryl bromide through the dropping funnel over a period of 2 hours while introducing dry nitrogen and heating on an oil bath of 110° C. After heating and stirring for 5 hours, the solvent was removed and the residue was recrystallized from ethanol/acetone to obtain 12 g of N-lauryl-2,2'-pyridylpyridinium bromide (hereinafter referred to as "2,2'--BPQ--C₁₂ "). The similar reactions were conducted with respect to other alkyl halides.

In 800 ml of methanol, 10 g of the above (2,2'-BPQ-C₁₂) and 200 g of the polymer PCS obtained in Example 1 were reacted at 60° C. for 50 hours to obtain in 207.2 g of the antibacterial polymer (2,2'-BPCQ-C₁₂).

TEST EXAMPLE 1

An antibacterial spectrum was measured in the following manner.

To a 500 ml-Erlenmeyer flask which was placed in a constant temperature bath of 30° C. equipped with a shaker was added 200 mg of the antibacterial polymer (PCS DB-B). To the flask was added 100 ml of bacteria suspension listed in Table 1 (6×10⁸ cells of bacteria of 30° C. and the mixture was shaked immediately. Each 1 ml of the mixture was sampled 0, 2 and 5 minutes after the addition of the bacteria suspension. The sample was immediately diluted with sterile isotonic sodium chloride solution in 10, 100 and 1000 times in dilution rate and then spread on nutrient agar plates.

Survival rate (%) was determined by measuring the survived bacteria in the colony after cultivation at 37° C. for 24 hours.

The results are given in Table 1.

                  TABLE 1                                                          ______________________________________                                                              Survival rate (%)                                                                after   after                                           Bacteria               2 min.  5 min.                                          ______________________________________                                         Gram positive bacteria                                                         Pseudomonas aeruginosa IFO 3080                                                                       0.07    0                                               Pseudomonas aeruginosa ATCC 10145                                                                     0       0                                               Escherichia coli K12 OUT 8401                                                                         0       0                                               Escherichia coli IFO 3301                                                                             0       0                                               Proteus vulgaris Ox.sub.19 RIMD                                                                       38.52   5                                               Gram negative bacteria                                                         Staphylococcus aureus NIHJ-JCI                                                                        0       0                                               Bacillus subtilis var. niger OUT 4380                                                                 0       0                                               Bacillus cereus IFO 3001                                                                              0       0                                               Bacillus megaterium IFO 3003                                                                          28.61   0                                               ______________________________________                                    

TEST EXAMPLE 2

Five kinds of sheets were prepared by mixing the components listed in Table 2 under the following conditions.

(a) mixing roll ; D=10in. 16 rpm

(b) roll temperature×time ; 140°˜145° C.×5 min.

(c) thickness of sheet ; 0.5 mm

Each of the obtained sheets was checked for antibacterial activity against mould according to JIS Z2911. The results were shown in Table 3.

                  TABLE 2                                                          ______________________________________                                         No.             1      2      3      4    5                                    ______________________________________                                         PVC (.sup.--P = 1100)                                                                          100    100    100    100  100                                  Plasticizer (DOP)                                                                               48     48     48     48   48                                  Stabilizer (Mark OF - 23)                                                                       2      2      2      2    2                                   PCS - B         --     0.10   0.15   0.20 0.30                                 Content of PCS-B (wt. %)                                                                       0.00   0.067  0.100  0.133                                                                               0.200                                ______________________________________                                    

                  TABLE 3                                                          ______________________________________                                                      Days                                                              Bacteria    No.    5     10    15  20    25  28                                ______________________________________                                         Aspergillus niger                                                                          1      +     +s    +s  +s    +s  +s                                IFO 4414    2      -     -     -   -     +   +                                 3           -      -     -     -   -     +                                     4           -      -     -     -   -     -                                     5           -      -     -     -   -     -                                     Penicillium citrinum                                                                       1      +     +s    +s  +s    +s  +s                                IFO 6026    2      -     -     -   -     +   +                                 3           -      -     -     -   -     +                                     4           -      -     -     -   -     -                                     5           -      -     -     -   -     -                                     Rhizopus stolonifer                                                                        1      +     +s    +s  +s    +s  +s                                IFO 5411    2      -     -     +   +     +   +                                 3           -      -     -     -   -     +                                     4           -      -     -     -   -     -                                     5           -      -     -     -   -     -                                     ______________________________________                                    

In Table 3, Nos. 1˜5 correspond respectively 0, 0.067, 0.100, 0.133 and 0.200wt. % of (PCS-B) to PVC.

+; mycelial growth

s ; sporulation

-; no growth

TEST EXAMPLE 3

The antibacterial polymer (2,2'-BPCQ-C₁₂) was checked for antibacterial activity with use of 10 mg thereof in the same manner as in Test Example 1. The results were shown in Table 4.

                  TABLE 4                                                          ______________________________________                                                        Survival rate (%)                                                                after     after   after                                       Bacteria         10 min.   20 min. 30 min.                                     ______________________________________                                         Escherichia coli K12 OUT8401                                                                    8.0       0       0                                           ______________________________________                                     

We claim:
 1. An antibacterial polymer containing a repeating unit of the formula ##STR4## l is 20 to 2000, n is a number of at least 1000, X and Z are the same or different and are an anion, R is alkyl group having 6 to 18 carbon atoms. 